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Published on: 7/21/2026

What are the differential diagnoses for unilateral tonsillar enlargement?

Yoshinori Abe

Reviewed by Yoshinori Abe, MD

Internal Medicine

Unilateral tonsillar enlargement—when one tonsil is noticeably larger than the other—can signal a range of underlying issues. Common causes include bacterial or viral infections (such as tonsillitis, peritonsillar abscess, or mononucleosis), benign growths, and less commonly, malignancies like lymphoma or squamous cell carcinoma. Other contributors may include chronic inflammation, tonsil stones, or asymmetry from prior infections. Because the causes vary widely in severity, prompt evaluation by a healthcare provider is essential for accurate diagnosis and treatment.

Not sure what's causing your symptoms? Waiting and worrying rarely helps—and asymmetric tonsils warrant timely attention. Take a free, instant, online symptom check to explore possible causes based on your specific symptoms and get clear guidance on what to do next. It's fast, private, and can help you decide whether to see a doctor urgently or monitor at home.

Reviewed for medical accuracy: 07/20/2026

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Important Next Steps

Learn likely causes of tonsil enlargementDiscover if your tonsil swelling needs careFind out if swollen tonsils could be seriousSee OTC options for tonsil swelling reliefFind ENT doctors for tonsil enlargementUnderstand medically proven home care for tonsilsCheck symptoms behind one-sided tonsil enlargement

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Explanation

Unilateral tonsillar enlargement means that one tonsil is bigger than the other. This can happen for several reasons:

  1. Infections: Sometimes, a sore throat or other infections can cause one tonsil to swell more than the other.

  2. Lymphoma: This is a type of cancer that can affect the tonsils, making one side grow larger.

  3. Other Conditions: Other health issues might also cause one tonsil to get bigger.

It is important to see a healthcare provider to find out why one tonsil is bigger. If you're experiencing symptoms like unilateral tonsillar enlargement, you can start by using a free AI symptom checker to help understand potential causes before your appointment. Each person's situation is different, so getting a check-up is a good idea if you notice this happening.

(References)

  • Cortez EA, Mattox DE, Holt GR, & Gates GA. (1979). Unilateral tonsillar enlargement. Otolaryngology and head and neck surgery, 530694.

  • Berkowitz RG, & Mahadevan M. (1999). Unilateral tonsillar enlargement and tonsillar lymphoma in .... The Annals of otology, rhinology, and laryngology, 10527279.

  • Guimarães AC, de Carvalho GM, Correa CR, & Gusmão RJ. (2015). Association between unilateral tonsillar enlargement and .... Critical reviews in oncology/hematology, 25487766.

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